Documentation for cranking amps for the NHC250 and 6CTA?

[LCA078]

I know the military prefers over to have over 2,000 CCA available with their battery set up but I'm curious if there is any Cummins documentation on cranking amps needed for the M939 series. The reason is I'm looking at a getting a couple new Group 31 batteries and will need to determine if I go with the higher CCA (950-1000) or the lower (750-800) from the same family. Reserve is effectively the same on both (190 vs. 170) so just wondering about needed CCA. The reason I'd like to go with the lower CCA is I understand the plates are thicker in the lower CCA and generally last longer in rough riding vehicles. But to the point, I know I CAN crank my NHC250 with 2 group 65's at 700 CCA as I've done it many times but not sure I want to put that much strain on the starter if I'm on the edge of cranking requirements. I just haven't seen any literature (not folklore) on what is required for our trucks.

 

[DeMilitarized]

I know the military prefers over to have over 2,000 CCA available with their battery set up but I'm curious if there is any Cummins documentation on cranking amps needed for the M939 series. The reason is I'm looking at a getting a couple new Group 31 batteries and will need to determine if I go with the higher CCA (950-1000) or the lower (750-800) from the same family. Reserve is effectively the same on both (190 vs. 170) so just wondering about needed CCA. The reason I'd like to go with the lower CCA is I understand the plates are thicker in the lower CCA and generally last longer in rough riding vehicles. But to the point, I know I CAN crank my NHC250 with 2 group 65's at 700 CCA as I've done it many times but not sure I want to put that much strain on the starter if I'm on the edge of cranking requirements. I just haven't seen any literature (not folklore) on what is required for our trucks.

I can crank and start my c12 on 2 650cca batteries (it doesnt like it but it does it) and my 8.3 will crank all day on 2 group 31 batteries 1000 cca

 

[LCA078]

I can crank and start my c12 on 2 650cca batteries (it doesnt like it but it does it) and my 8.3 will crank all day on 2 group 31 batteries 1000 cca

That makes sense as I think the C12 is about 40% larger displacement than the 8.3. The C12 is still not as big as the NHC250 in liters but I can see where 2 650cca batteries in series will struggle some on the crank. It's just a lot of displacement to compress on two small batts. And I'd say it ain't gonna work if the weather is cold.

I'm curious as I can find random Cummins engine spec sheets online that talk about needing about 1,200cca for 8.3 in marine applications but I believe that's all for 12v systems. When I started googling, I saw the boat forums talk about using a single 4D or 8D to crank their 8.3s and how some guys go to double group 31s or 27s to save weight and make replacement easier. I bet if I had to lift an 8D out of the bottom of a boat transom I would never complain about changing batteries (or tires) ever again on our trucks...

Anyway, just wondered if there was something "official" on battery requirements for our trucks...